This invention lies in the field of gas turbine, or jet, engines which produce reaction thrust by ejecting a high velocity stream of gas from the exhaust nozzle or tail pipe of the gas turbine. Airplanes equipped with jet engines have very high flying speeds and very high landing speeds. The landing speeds place an excessive burden on the wheel brakes because of the low drag effect of the airplanes themselves and also because of the residual thrust of the engines. It is common practice to reduce the burden of the brakes by the use of thrust reversers or spoilers, which also may be used in the flight regime to facilitate various maneuvers.
The various types of apparatus for modifying thrust which are presently in use perform their intended functions quite satisfactorily, but they have a common drawback which is a matter of concern. The blocking effect which deflects the exhaust gases laterally also produces a back pressure effect which in turn tends to reduce the mass flow at any given operating condition. Such reduction is deleterious to the engine and it is highly desirable to eliminate it if possible.